Process upgrade refers to start, in a system supporting multiple processes, a new process, copy the service in a source process to the new process, and deregister the source process. As a result, the process is upgraded. Process upgrade allows a process to be upgraded to a higher version so that defects or loopholes in the version of the source software process can be fixed.
In the case where the source process is an on-line process, i.e. Transfer Control Protocol (TCP) socket process, it is not easy to conduct an on-line upgrade for TCP socket process due to the complexity of TCP connection. Generally, socket connection needs to be released first. After the source process is upgraded to a new connected process, the socket connection is re-established. Therefore, due to the interruption in the socket connection during an upgrade procedure, data loss and process instability may be incurred and a far end entity coupled to the socket interface may also perceive the update of the local entity.